In the drilling, downhole completion, production, transport, storage, and processing of crude oil and natural gas, including waste water associated with crude oil and gas production, and in the storage of residual fuel oil, H2S and/or mercaptans are often encountered. The presence of H2S and mercaptans is objectionable because they often react with other hydrocarbons or fuel system components. Another reason that the H2S and mercaptans are objectionable is that they are often highly corrosive. Still another reason that H2S and mercaptans are undesirable is that they have highly noxious odors. The odors resulting from H2S and mercaptans are detectable by the human nose at comparatively low concentrations and are well known. For example, mercaptans are used to odorize natural gas and used as a repellant by skunks and other animals.
The predominant H2S and mercaptan scavengers for natural gas and crude oil are monoethanolamine (MEA) triazines and monomethylamine (MMA) triazines. These compounds contain nitrogen and when used in sufficient concentration can cause problems for certain refineries. There have been instances where operators have required the use of a non-nitrogen containing H2S scavenger. Glyoxal (C2H2O2) or acrolein (C3H4O) has been used as H2S scavengers in these instances. Glyoxal is a slow acting scavenger and may be corrosive to mild steel. Acrolein is effective scavenger but an extremely toxic substance which operators do not like to use.
It would be desirable if a new non-nitrogen-containing H2S and mercaptan scavenger could be discovered which is very effective, but which overcomes the deficiencies of prior scavengers.